In some uses of plastic pipe, it is a requirement that the pipe be perforated. In one example only, underground profiled drainage pipe is provided with small cuts or slits spaced from one another around the troughs of the profiled pipe.
In the past, different devices have been either used or proposed for perforating such pipe. U.S. Pat. Nos. 4,180,357 and 4,218,164 both issued to Gerd Lupke disclose tube perforating devices in the form of a plurality of screw-like cutters rotatably mounted on fixed shafts around a center bore through which tubing is passed for perforation by the screw-like members. Although the devices in both of these patents are very efficient in operation, they are not easily adjusted for different tube diameters.
U.S. Pat. Nos. 5,381,711 and 5,385,073 both owned by Truemner et al, disclose tube perforators having driver cutter wheels supported by drive shafts at different positions around the perforators. According to both of these patents the drive shafts are at an angle, i.e. not parallel to the axis of the tube passed through the perforator. The angling of the drive shafts produces a tipping of the cutter wheels which, according to each of the patents, helps keep the wheels in the troughs of the tube and to accommodate very minor fluctuations in the tubing. In addition, according to each of these patents the driver cutter wheels are inter-changeable with other driver cutter wheels to accommodate more substantial variances in the tubing such as for example, tubing of different diameters.